We start with simple positions where a discovered attack is ready to be executed: one piece masks another, and both have good targets. Visually most of these positions will take a common form: a bishop moves from the middle of the board to the edge near the enemy king, where it gives check or makes a capture; in the process it unmasks an attack up the board by a rook or queen, usually made from the back rank.
In the diagram to the left, notice the position of White’s rook and bishop on the d-file—a classic kernel of a discovered attack. The bishop masks the rook; if it can vacate the file in a forceful enough manner—e.g., with a check—White will have the capture RxQ a move later. So White plays Bxh7+; Black is forced to spend a move protecting his king with KxB; and now White takes Black's queen with his rook. After Black recaptures with RxR, White has traded a bishop and rook for a queen and a pawn.